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Q6. A vapour compression refrigeration plant uses R134a. The refrigerant enters the compressor at a pressure and temperature of 1.6393 bar and -5℃ respectively and undergoes isentropic compression to 13.174 bar. The liquid refrigerant leaves the condenser at a temperature of 35℃. The cooling load is 250 kW.

(a) Sketch The cycle on a pressure-specific enthalpy diagram indicating areas of heat and work transfer. (2)

(b) Sketch The cycle on a Temperature- specific entropy diagram indicating areas of superheat and work transfer. (2)

(c) Calculate EACH of the following:

(i) The mass of dry saturated vapour entering the evaporator; (4)

(ii) The compressor power; (4)

(iii) The coefficient of performance; (2)

(iv) The Carnot coefficient of performance between the same temperature limits. (2).